It would not be possible to measure the fructose and glucose in the sample using just K-FRUC. 

To measure glucose and fructose, it would be necessary to perform the hydrolysis of any sucrose and starch in the sample using enzyme solution A, in duplicate

One of the duplicates would proceed to borohydride treatment for conversion of these sugars to sugar alcohols to allow for subsequent analysis of fructan (i.e inulin) component only.

The 2nd duplicate at that point (i.e. before borohydride treatment) could be used for sugar analysis through another method such as K-FRUGL for glucose / fructose measurement